Officials and volunteers in Bangladesh say heavy flooding is worsening in parts of the country, with more than one million villagers marooned or leaving their homes for higher ground.
Water levels at major rivers were rising on Tuesday at around two dozen points in 20 districts.
Many new areas in northern, northeastern and central Bangladesh have been affected over the last 24 hours, said an executive engineer with the Water Development Board.
The floods started late last month, and after briefly easing continued to worsen, destroying crops and driving people from their homes in several impoverished regions.
The Bangladesh Flood Forecasting and Warning Center, or FFWC, reports there is no relief in sight for northwest and central Bangladesh. One forecaster at the FFWC told the French news agency, AFP, this could be the worst flooding in a decade.
Extremely heavy rain across the border in upstream India and Bangladesh triggered the second wave of flooding while the first wave has not yet receded.
The U.N.'s Relief Web reports the Bangladesh government allocating food and cash for immediate response in the affected areas with 975 flood shelters opened, and 175 medical teams mobilized.
Heavy monsoon rains are expected throughout the country in coming days that could further worsen the situation.
The monsoon season in the region runs from June through September, swelling Bangladesh's 230 rivers, including 53 shared with India.